Optical fiber organizer

ABSTRACT

An optical fiber organizer for organizing a plurality of uncut optical fibers of an optical fiber cable, comprising a plurality of optical fiber storage trays, the construction of the organizer being such that: 
     (a) the uncut optical fiber(s) of each single optical fiber circuit; or 
     (b) the uncut optical fibers of each single optical fiber cable element; may be stored separately from the optical fiber(s) of each other circuit or element, on respective individual storage trays.

The present invention relates to the organization of optical fibres,e.g. in an optical fibre cable splice closure.

Many different designs of optical fibre organizer are known. Forexample, WO 95/07480 (Raychem) discloses a base for an optical fibreorganizer, which comprises: a first passage along one longitudinal edgeportion for incoming fibres; a second passage along an oppositelongitudinal edge portion for outgoing fibres; a plurality of firstfibre guides separated from one another along the length of the base andextending from the first passage across the base towards the secondpassage where fibres in said guides are directed away from the plane ofthe base; a plurality of second fibre guides separated from one anotheralong the length of the base and extending from the second passageacross the base towards the first passage where fibres in said guidesare directed away from the plane of the base.

WO 95/25978 (Raychem) discloses an apparatus for arranging a pluralityof stacks of optical fibre splice organizers in a closure, comprising aframe and at least two optical fibre splice organizer supports locatedon the frame, each organizer support being arranged to support a stackof organizers. The frame may be elongate and the organizer supports mayeach support a stack of organizers which extends laterally with respectto the frame. The organizer supports may be in one or more pairs, thesupports of each pair being arranged back-to-back.

WO 95/07475 (British Telecom) discloses an optical fibre managementsystem comprising a plurality of splice trays arranged in a stack. Eachsplice tray has a main body portion for holding at least one splice, andfor storing fibres leading to the splice(s), and a fibre entry/exitportion for feeding fibre to/from the main body portion. Each tray ismounted in the stack so as to be movable from a stacked position, inwhich it is aligned with the other trays, to first and second operatingpositions in which the fibre entry/exit portion and the main bodyportion respectively are accessible. A related patent application, WO95/07486 (British Telecom), discloses so-called “single circuitmanagement” of spliced fibres or unspliced cut dark “customer” fibres.Single circuit management is the management of optical fibres byseparating individual optical fibre circuits from each other.

GB-A-2305739 (Telephone Cables Limited) discloses an optical fibresplice tray which comprises a body with a plurality of splice holders atfixed locations. Fibre paths are provided on the body leading from fibreentry points to the splice holders. Hinged storage leaves are alsomounted on the body.

According to a first aspect, the invention provides an optical fibreorganizer for organizing a plurality of uncut optical fibres of anoptical fibre cable, comprising a plurality of optical fibre storagetrays, the construction of the organizer being such that:

(a) the uncut optical fibre(s) of each single optical fibre circuit; or

(b) the uncut optical fibres of each single optical fibre cable element;

may be stored separately from the optical fibre(s) of each other circuitor element (as the case may be) on respective individual storage trays.

The invention also provides such an organizer in which the uncut opticalfibres are (i.e. have been) so installed on the storage trays.

According to a second aspect, the invention provides a method oforganizing a plurality of uncut optical fibres of an optical fibrecable, on an optical fibre organizer, the organizer comprising aplurality of optical fibre storage trays, the method comprising storing:

(a) the uncut optical fibre(s) of each single optical fibre circuit; or

(b) the uncut optical fibres of each single optical fibre cable element;

separately from the optical fibre(s) of each other circuit or element(as the case may be) on respective individual storage trays.

By “uncut” optical fibres is meant optical fibres which enter and exitthe organizer without being severed. Such fibres are sometimes referredto as “express” fibres, since they extend through the organizer withoutbeing spliced, connected or broken for any other reason. The inventionhas the advantage that, for the first time, it enables such uncut fibresto be stored in single circuits, or single cable elements (as the casemay be). This is advantageous because the fibre(s) of individualcircuits or cable elements which are not spliced to other fibres whenthe organizer is initially installed on the cable may later be splicedto other fibres without disturbing the uncut fibres of other circuits orcable elements (as the case may be). This vastly reduces the risk ofaccidentally introducing signal losses into the circuits, or cableelements, of other uncut fibres, or damaging the other uncut fibres,during the splicing procedure. The splicing of fibres which hadinitially remained uncut (and unspliced) is carried out, for example,when adding new subscribers, or new services, to the network.

In contrast with the present invention, the various optical fibreorganizers disclosed in the prior publications mentioned earlier, areincapable of storing uncut fibres in single circuits or single cableelements. For example, the optical fibre management system disclosed inWO 95/07486 is able to store only severed optical fibres (i.e. splicedfibres or unspliced dark “customer” fibres). This is because the fibreswhich are stored in single circuits must have their ends threadedthrough openings which are closed in cross-section. Uncut fibres areinstead retained bundled in their cable tubes which are in turn bundledtogether and looped around the so-called break-out tray. Similarly, thesplice tray arrangement of GB-A-2305739 requires the optical fibre endsto be threaded through holes punched in the hinged leaves (see FIG. 5 ofthat document).

For the avoidance of doubt, it should be noted that a single circuitmay, for example, comprise a single optical fibre or a pair of opticalfibres, depending upon the transmission technique used. Also, a cableelement is a defined group of optical fibres in a cable, for example agroup of fibres from a single tube of the cable, or a group of fibresfrom a single slot of a slotted core cable.

In a preferred embodiment of the invention, the construction of theorganizer is such that it comprises a plurality of optical fibre guidesintended for uncut optical fibre(s), every one of which is open oropenable in transverse cross-section, thereby permitting side-entry ofthe uncut optical fibre(s) into the guide.

The organizer may advantageously further comprise a support whichcomprises:

(i) a plurality of tray mounting means to which the optical fibrestorage trays are attached, thereby mounting the trays on the support;and

(ii) a plurality of guides for guiding the optical fibre(s), the or eachsaid guide being open or openable in transverse cross-section, therebypermitting side-entry into the guide of optical fibre(s) extending froma respective optical fibre storage tray mounted on the support.

According to a third aspect, the invention provides an optical fibreorganizer which comprises a support, the support comprising:

(i) one or more tray mounting means for attachment to at least oneoptical fibre storage tray, thereby to mount the tray on the support;and

(ii) at least one guide for guiding at least one optical fibre, the oreach said guide being open or openable in transverse cross-sectionthereby permitting side-entry into the guide of at least one opticalfibre extending from a respective optical fibre storage tray mounted onthe support.

The mounting means may be separate or separable from the guide(s). Morepreferably, however, the mounting means is/are integrally formed (e.g.moulded) with the guide(s).

According to a fourth aspect, the invention provides an optical fibreorganizer which comprises a unitary support, the support comprising:

(i) one or more tray mounting means for attachment to at least oneoptical fibre storage tray thereby to mount the tray directly on thesupport; and

(ii) a least one guide for guiding at least one optical fibre extending,in use, from an optical fibre storage tray mounted on the support.

The or each guide of the fourth aspect of the invention is preferablyopen or openable in transverse cross-section in use, thereby permittingside-entry into the guide of a least one optical fibre extending from arespective optical fibre storage tray mounted on the support.

The support preferably comprises a plurality of guides. Additionally oralternatively, the support may comprise a plurality of tray mountingmeans for attachment to a plurality of optical fibre storage traysthereby to mount the trays on the support. In preferred embodiments,therefore, the organizer comprises a plurality of said optical fibrestorage trays, each of which is attached to at least one said traymounting means, the trays thereby being mounted directly on the support.

The or each tray mounting means is preferably arranged with respect toat least one respective guide such that at least one optical fibreextending, in use, from a storage tray attached to one or more traymounting means may be guided by the or each respective guide without theoptical fibre being bent below its critical bend radius. Advantageouslythe or each guide may include at least one ramp arranged to guide atleast one optical fibre between the guide and an optical fibre storagetray attached, in use, to the respective tray mounting means. The oreach guide preferably includes at least two ramps, for example fourramps.

In preferred embodiments, each guide preferably comprises at least onegroove in the support.

Each guide may advantageously be arranged such that at least part of itis substantially parallel to the or each optical fibre storage traymounted, in use, on the support. Preferably, the support furthercomprises at least one routing means arranged substantiallyperpendicularly to this part of the or each guide, for routing one ormore optical fibres from the guide(s) to the exterior of the support.The routing means may, for example, comprise at least one channel.

The support is preferably in the form of a plate.

The organizer most preferably comprises a plurality of supports,preferably attachable either directly or indirectly togetherside-by-side to form a larger support. Advantageously, this indirectattachment may be by means of a support frame to which the supports areattachable side-by-side to form a larger support.

According to a fifth aspect, the invention provides a kit of parts forforming an optical fibre cable closure, comprising an optical fibreorganizer according to the previously mentioned aspects of theinvention, and a casing for enclosing the optical fibre organizer. Thecasing preferably comprises a base containing cable ports, and agenerally dome-shaped cover attachable to the base, the optical fibreorganizer being attachable to the base.

The invention will now be described, by way of example, with referenceto the accompanying drawings, of which:

FIGS. 1A-1C show a support according to the invention, for hingedoptical fibre storage trays;

FIGS. 2A-2B show another support according to the invention, for hingedoptical fibre storage trays; and

FIG. 3 shows an assembled optical fibre organizer according to theinvention attached to a base of a cable closure.

FIG. 1 shows a modular support plate 1 comprising a plurality of partsof mounting means 3 in the form of integral moulded protrusions standingup from the plate. The mounting means 3 contain apertures for receivinghinge pins formed on the storage trays. The storage trays are thereforehinged with respect to the support plate in use. Each of the trays maytherefore be accessed by pivoting all of the trays on one side of thetray, away from the tray. FIG. 1 also shows flexible tines 4 (alsoprotruding from the support plate) which lock the hinge pins of thetrays in the mounting pins 3.

Each pair of mounting means 3 is associated with a respective guide 5which is in the form of an open-sided groove in the plate. In use, anoptical fibre storage tray 7 (see FIG. 3) is attached to a particularpair of mounting means 3, and one or more optical fibres or ribbons ofoptical fibres extending from the tray is received in the respectiveguide groove 5. Because the guide grooves 5 are open-sided, such opticalfibres are inserted into them by “side-entry”, i.e. without having tothread the fibres through an aperture. This has the advantage ofenabling uncut (looped) optical fibres to be stored in the trays, forexample in single circuits or single elements.

Each guide groove 5 includes four ramps 9 which, in use, guide one ormore optical fibres or ribbons of optical fibres between the guide andits respective storage tray, i.e. the ramps guide the fibres away fromthe support plate towards the hinged tray mounted on the support plate.The ramps are situated in a relatively wide central region 11 of eachguide. At each end 13 of the guide, the guide is narrower in width andis also curved in the plane of the support plate. At the ends of theguides, and extending substantially perpendicularly to the straightcentral regions of the guides, are optical fibre routing channels 15,for routing the optical fibres or ribbons from the guides 5 to theexterior of the organizer. An optical fibre, or a ribbon of opticalfibres, may therefore extend from the exterior of the organizer (e.g.from a cable) along one routing channel 15 and into one end 13 of arespective guide 5. The fibre or ribbon may extend along the guide 5across part of the width of the support plate and up one or both rampsinto a storage tray mounted to the support plate (mounted by attachmentto the respective mounting means 3). The fibre or ribbon may be loopedone or more times in the storage tray, extend out of the tray and downthe opposite ramps into the same guide 5. It will extend along the guide5 past the first ramps out of the opposite end of the guide, into theother routing channel 15 and then to the exterior of the organizer.

When ribbons of optical fibres are used, the major width of the ribbonswill generally be substantially perpendicular to the plane of thesupport plate in the routing channels 15 and the relatively narrow endregions 13 of the guides 5. However, in the relatively wide centralregions 11 of the guides, the ribbons will normally twist through about90° so that in the regions where they are guided towards the trays bythe ramps 9 their major widths will generally be substantially parallelto the plane of the support. The dimension of the guides are preferablypredetermined to cause or facilitate this change in the orientation ofthe ribbons which is required because optical fibre ribbons generallymust not be bent about an axis which is perpendicular to their majorwidth.

The support plates illustrated in FIGS. 2A and 2B are similar to thesupport plate illustrated in FIG. 1, except that the routing channelscomprise a plurality of narrow channels 17 designed to route opticalfibre ribbons orientated such that their major width is substantiallyperpendicular to the plane of the support plates. In FIG. 2B two supportplates are arranged side-by-side, thereby forming a larger supportplate.

FIG. 3 shows an optical fibre organizer 19 which has been assembled andattached to a base 21 of a cable closure. The organizer 19 comprises asupport frame 23 and a storage module 25 attached to the support frame.The storage module 25 comprises a support plate 27 (of similar, butslightly different, design to the support plate shown in FIG. 1)supporting a plurality of hinged optical fibre storage trays 7. Eachsupport plate 27 includes attachment devices 29 which are interlocked(by a snap-fit) with the support frame 23. The support frame 23comprises two pairs of spaced-apart elongate parts 31 which areinterconnected by an elongate cross-member 33. Each elongate part 31 isanchored to the base 21 of the closure.

The routing of the uncut optical fibre(s) of a single circuit or asingle cable element, on the organizer, is shown schematically by meansof a thick black line 34. The path of the optical fibre(s) 34 is alsoillustrated schematically adjacent to the organizer. (The path will bedescribed with reference to a single fibre, for clarity). The fibreextends from the region of the organizer which is adjacent to the base21 of the closure through open-sided guides 36, 38 and 42, and throughthe open-sided routing channel 15 on the support plate 27. The fibrethen extends into an open-sided guide groove 5 (see FIGS. 1 and 2) inthe support plate, and towards the opposite edge of the support plate.The fibre then extends into a storage tray 7 which is associated withthat particular guide groove 5, it is looped one or more times in thetray (depending upon the length of fibre to be stored), and then extendsout of the tray and back into the guide groove 5. The fibre extendsalong the guide groove 5 once more, and then extends out of the oppositeend of the guide groove to that through which it entered. The fibre thenextends along a routing channel 15 situated beyond this opposite edge ofthe guide groove back towards the base region of the cable closure.

An optical fibre cable (not shown) carrying the uncut optical fibreswhich are stored on the organizer in single circuits, or single elements(as the case may be) enters the cable closure through an oval port 44 inthe base of the closure. In particular, a loop of the cable is fedthrough this port, and the optical fibres are exposed and organised asdesired in the closure. Normally, some of the optical fibres will be cutand spliced to optical fibres from other cables which extend into theclosure through cable ports 46. The splices and associated fibre lengthsare also stored on respective storage trays 7, in single circuits, orsingle cable elements (as the case may be). The organizer, and cableclosure, will therefore normally store both uncut (and thereforeunspliced) and cut (and spliced) fibres, in single circuits or singlecable elements.

What is claimed is:
 1. An optical fiber organizer comprising: aplurality of storage trays organizing a plurality of uncut opticalfibers of an optical fiber cable, each storage tray comprising a firstoptical fiber guide having an opening in a transverse cross-section forside-entry of at least one uncut optical fiber therein, the at least oneuncut optical fiber being separate from the other plurality of uncutoptical fibers; and at least one support plate connected to saidplurality of storage trays, said at least one support plate comprising aplurality of second optical fiber guides, each second optical fiberguide having an opening in a transverse cross-section for side-entry ofthe at least one uncut optical fiber therein.
 2. An optical fiberorganizer according to claim 1, wherein each storage tray comprisesconnection means for connecting to said at least one support plate; andwherein said connection means is adjacent said first optical fiberguide.
 3. An optical fiber organizer according to claim 2, wherein saidconnection means is arranged with respect to said first optical fiberguide such that the at least one uncut optical fiber is guided by saidfirst optical fiber guide without being bent below a critical bendradius associated therewith.
 4. An optical fiber organizer according toclaim 1, wherein each second optical fiber guide comprises at least oneramp for guiding the at least one uncut optical fiber between saidsecond optical fiber guide and said storage tray connected thereto. 5.An optical fiber organizer according to claim 4, wherein each secondoptical fiber guide comprises four ramps.
 6. An optical fiber organizeraccording to claim 1, wherein each second optical fiber guide comprisesat least one groove.
 7. An optical fiber organizer according to claim 1,wherein each second optical fiber guide is substantially parallel tosaid respective storage tray connected thereto.
 8. An optical fiberorganizer according to claim 1, wherein said at least one support platefurther comprises routing means substantially perpendicularly to saidsecond optical fiber guide for routing the plurality of uncut opticalfiber cables external to said at least one support plate.
 9. An opticalfiber organizer according to claim 8, wherein said routing meanscomprises at least one channel.
 10. An optical fiber organizer accordingto claim 1, wherein said at least one support place comprises aplurality of support plates connected side-by-side to form a largersupport plate.
 11. An optical fiber organizer according to claim 1,further comprising a support frame connected to said at least onesupport plate.
 12. An optical fiber organizer according to claim 1,further comprising a casing for enclosing the optical fiber organizer.13. An optical fiber organizer according to claim 12, wherein saidcasing comprises: a base having at least one cable port for receivingthe optical fiber cable, and wherein the optical fiber organizer isconnected to said base; and a cover connected to said base.
 14. A methodof organizing a plurality of uncut optical fibers of an optical fibercable, the method comprising the steps of: separating at least one uncutoptical fiber from the plurality of uncut optical fibers using a storagetray comprising a first optical fiber guide having an opening in atransverse cross-section for side-entry of the at least one uncutoptical fiber therein; and routing the at least one uncut optical fiberusing a support plate connected to the storage tray, the support platecomprising a plurality of second optical fiber guides, each secondoptical fiber guide having an opening in a transverse cross-section forside-entry of the at least one uncut optical fiber therein.
 15. A methodaccording to claim 14, further comprising the step of connecting thestorage tray to the support plate using connection means adjacent thefirst optical fiber guide.
 16. A method according to claim 15, furthercomprising the step of guiding the at least one uncut fiber from thesecond optical fiber guide to the respective storage tray storage traywithout being the at least one uncut optical fiber below a critical bendradius.
 17. A method according to claim 14, wherein each support platecomprises at least one ramp; and the method further comprising the stepof guiding the at least one optical fiber between the second opticalfiber guide and the storage tray connected thereto using the at leastone ramp.
 18. A method according to claim 14, wherein each support platefurther comprises channels substantially perpendicularly to the secondoptical fiber guide; and wherein the method further comprises the stepof routing the plurality of uncut optical fiber cables external to thesupport plate via the channel.
 19. A method according to claim 14,further comprising the step of connecting supports plates side-by-sideto form a larger support plate.
 20. A method according to claim 19,further comprising the step of connecting a support frame to the supportplates connected side-by-side.
 21. A method according to claim 14,further comprising: connecting the optical fiber organizer to a basereceiving the optical fiber cable; and attaching a cover to the base.